These two pictures nicely show that the two spars are the only non-removable parts of the car structure forward of the firewall. The inner fenders are detachable splash shields, and the rest of the front bodywork unbolts and electrically disconnects, and is taken away to the front in one still- assembled piece if desired. After the tie rods (or pitman arm and idler arm) and brake lines etc are disconnected and the engine supported, the cross member with suspension attached to it unbolts from below.

The 544 crossmember is similar to the later one in these pictures-- your posting on King Pins of Dec 5 at 21:07 has a good rendering of it. There was a change in idler arm bracket attachment effective with (?) the B18 544's of '62-on; it bolts to the spar, opposite the steering box, instead of being welded to the crossmember. This would be of advantage if the 544 suspension and steering were kept (see Iadr's post on Swedish Classics forum) but the middle of the crossmember was altered to avoid the V8's front sump. (I see elsewhere that Econoline vans with 302's had the sump set somewhat further to the rear, compared to pass.car installations; this would help.)

The Canadian car that Phil posted the picture of appears to me to have the block/bellhousing joint set further back than the B18/20 does in the stock setup. The fact that the longer 302 engine fits behind a radiator in its original position is the clue. This rearward position will help with the sump/crossmember, fuel pump/steering box, and steering column/exh manifold conflicts, but not with detaching gearbox from engine etc while still in the car. The 544 footwells are narrow already, so pedal and foot accommodation will be challenged by a wider tranny tunnel that extends further back. I see some relief by modifying the brake and clutch pedal footpads to tall and narrow instead of wide and low, plus eliminating the foot switch for high beams like you did. (I don't fancy using an automatic.)

The 302's width across the heads (including iron exh manifolds except at their outlets for some versions) and width across the block at the crankcase (including starter) are both easily less than the space between a 544's spars. The starter is conveniently on the passenger side of the block. Motor mounts are at mid-length of the block, posing a mate-up problem. A custom additional crossmember attached like the original to the spar lower edge flanges, but further back, might carry motor mounts. It could be combined with the original: The original cross-member's center section might be modified and added to, being divided into two narrow front and rear cross-spans to straddle the engine's relocated sump, and to receive the motor mounts on their connecting, box-section side members-- making a #-shaped sub-frame or cradle, in effect.

The 302 is low- <8 inches from crank centerline/ bottom of block to top of exh manifolds. There will be lots of room in a 544 engine bay above the engine block and heads for induction system and alternator, accessories, etc, but not alongside the engine. Everything needing tinkering and maintenance ought to be up top where it can be reached. The heater would fit, as the photo shows, but may obstruct spark plug access on that side. Its air intake hose might detour via the fender, over the left front suspension, and only enter the engine bay back at the heater. Exh manifold config and headpipe routing will be interesting.